Jose Mourinho rued "incredible defensive mistakes" but remained optimistic after Chelsea dismantled Manchester United 4-0 on his return to Stamford Bridge.

Pedro scored within 30 seconds to give Mourinho's former employers the lead before Gary Cahill smashed in a second with Eden Hazard and N'Golo Kante sealing a resounding win in the second half.

But the Red Devils boss wants his side to focus on returning to winning ways in their upcoming matches following a tough run of fixtures.

He said: "In the first minute, you analyse the goal and you can see what happened - we made incredible defensive mistakes, individual defensive mistakes and you pay for that.

"In terms of points, it's zero points - if you lose 1-0 or 4-0 you lose three points. We are six points from the top of the league and now we have to win matches.

"We had a week where we have played two (title) candidates in Liverpool and Chelsea and now the other teams from the top five have to play among themselves, they have to draw and lose the points each. We need to win our matches now, which is not easy but we play Burnley, we play Swansea and West Ham and we need to win matches to close the gap."

Bailly has impressed since his summer move from Villarreal and limped off after 52 minutes with what Mourinho believes could be a long-term knee injury. "He is injured and I am afraid he is badly injured," the United manager said. "In his knee, in the ligament area. He feels that it is really bad."

Humiliating

On his reception at Stamford Bridge, Mourinho said: "I was not expecting anything different and the crowd behaved in the normal way so... nothing wrong."

He refused to elaborate on what he said to Chelsea boss Antonio Conte after the full-time whistle in what appeared to be a heated exchange between the two.

Conte, however, was unapologetic after the United boss spoke at length to the Italian at the final whistle, with suggestions the Portuguese had been annoyed that the Italian had encouraged the home support to cheer on the Blues when they were already 4-0 up.

Reports in Italian media said Mourinho told Conte: "You don't celebrate like that at 4-0, you can do it at 1-0, otherwise it's humiliating for us."

And the self-proclaimed Special One insisted the conversation should be private, despite choosing to conduct it in front of 41,000 people and the Stamford Bridge press box. "I speak to Conte, I don't speak to you (the media)," Mourinho said.

"It was me and Antonio and stays with me and him. Unless he wants to share."

Conte declined to do so.

"I've been a player too and I know how to behave," Conte said. "I always show great respect for everyone, including Manchester United.

"There was no incident, it was just a normal thing to do. I wasn't mocking anyone, I wouldn't do that."

The Chelsea head coach added in his post-match press conference: "Today it was right to call our fans in a moment (when) I was listening (to) only the supporters of Manchester United, at 4-0. The players, after a 4-0 win, deserved a great clap. It's very normal. If we want to cut the emotion we can go home and change our job."